MySQL利用procedure analyse()函数优化表结构

简介

procedure analyse()函数是mysql/' target='_blank'>mysql内置的对MySQL字段值进行统计分析后给出建议的字段类型。

语法

procesure analyse(max_elements,max_memory)

max_elements

指定每列非重复值的最大值，当超过这个值的时候，MySQL不会推荐enum类型。

max_memory

analyse()为每列找出所有非重复值所采用的最大内存大小。

实战演练

# 对t1表所有的列进行分析wing@3306>show create table t1;+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table                                                                      |+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+| t1  | CREATE TABLE `t1` ( `id` int(11) DEFAULT NULL, `name` varchar(16) DEFAULT NULL, `score` int(11) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8 |+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)wing@3306>select * from t1 procedure analyse(4);+---------------+-----------+-----------+------------+------------+------------------+-------+-------------------------+-------------+--------------------------------+| Field_name  | Min_value | Max_value | Min_length | Max_length | Empties_or_zeros | Nulls | Avg_value_or_avg_length | Std     | Optimal_fieldtype       |+---------------+-----------+-----------+------------+------------+------------------+-------+-------------------------+-------------+--------------------------------+| wing.t1.id  | 1     | 200000  |     1 |     6 |        0 |   0 | 100000.5000       | 116099.2790 | MEDIUMINT(6) UNSIGNED NOT NULL || wing.t1.name | 000jxc6V | zzznmkcX |     8 |     8 |        0 |   0 | 8.0000         | NULL    | CHAR(8) NOT NULL        || wing.t1.score | 1     | 100    |     1 |     3 |        0 |   0 | 50.4889         | 28.8768   | TINYINT(3) UNSIGNED NOT NULL  |+---------------+-----------+-----------+------------+------------+------------------+-------+-------------------------+-------------+--------------------------------+3 rows in set (0.14 sec)

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